【作者】 李永振；

【导师】 高天翔；

【作者基本信息】 中国海洋大学 ， 渔业资源， 2010， 博士

【摘要】 珊瑚礁是高生产力的海洋生态系统。在我国南海,东沙、西沙、中沙和南沙群岛是典型的珊瑚礁生态系统,2002年被确定为全球十大珊瑚礁保护区之一。南海珊瑚礁渔业作为我国四大海区中特有的渔业类型,在南海渔业和海洋权益维护方面,都具有其特殊的地位和作用。与南海北部海域相比,由于航程遥远,海况恶劣,调查手段和作业季节制约,以及周边复杂的政治环境的限制等诸多因素,南海“四沙”珊瑚礁渔业资源的调查和研究十分薄弱。本项研究系统地收集和整理了南海珊瑚礁渔业资源调查的历史资料和数据,对南海珊瑚礁海域鱼类物种多样性进行了大尺度分布格局探讨,并就部分典型礁栖性种类的生态分布和渔获分布情况进行了简要简述,在此基础上,分析了主要经济种类的繁殖、年龄与生长,并对其种群动态进行了评估,结合鱼类生物学特征提出开捕规格建议,为南海珊瑚礁鱼类资源的开发和可持续利用提供参考。(1)物种多样性大尺度分布格局研究表明,目前东沙、西沙和中沙、南沙群岛分别记录鱼类514种、632种和548种,记录的鱼类物种数目均少于预测数目,也少于全球其他生境相似的海域。计算得出的分类学多样性指数的平均分类差异指数△+和分类差异变异指数∧+,东沙△+为55.1、∧+为121,西沙和中沙△+为60.2,∧+为164,南沙△+为56.6,∧+为150,四大瑚礁海域鱼类△+均小于南海北部陆架和东海陆架,而∧+的分布完全相反,高于陆架区。(2)根据渔获组成,参照渔获重量和尾数所占百分比、在各调查站位捕获的频率以及Pinkas(1971)的相对重要性指数IRI综合考虑,黑梢真鲨Carcharhinus limbatus、长吻六鳃鲨Hexanchus nakamurai、路氏双髻鲨Sphyrna lewini、灰三齿鲨Triaenodon obesus、灰六鳃鲨Hexanchus griseus、尖吻鲭鲨Isurus oxyrinchus、大眼角鲨Squalus megalops、长鳍真鲨Carcharhinus longimanus、鼬鲨Galeocerdo cuvier、迈氏条尾魟Taeniura meyeni等10种软骨鱼类和黄斑胡椒鲷Plectorhinchus flavomaculatus、胡椒鲷Plectorhinchus pictus、长吻裸颊鲷Lethrinus miniatus、星点鲹Caranx stellatus、棘鳞蛇鲭Ruvettus pretiosus、珍鲹Caranx ignobilis、红钻鱼Etelis carbunculus、丝鳍紫鱼Pristipomoides filamentosus、裸狐鲣Gymnosarda unicolor和星斑叉鼻纯Arothron stellatus等9种硬骨鱼类是珊瑚礁区的主要渔业资源种类,简述它们各自的生态分布特征,并分析了在西沙、中沙和南沙群岛礁区的单位努力量渔获量的分布。(3)分析了21种306尾软骨鱼类和93种1048尾硬骨鱼类的性腺成熟度。软骨鱼类的性比接近1：1,性腺成熟度以Ⅱ期占优势,表明多数种类在样品采集时间不是繁殖季节,极少数种类如黑梢真鲨和锯齿刺鲨Centrophorus tessellatus等,繁殖季节应当在5～7月份。根据收集到的资料,多数软骨鱼类为卵胎生或胎生,妊娠期一般为5～10个月或更长时间,胚胎数也多在1～5～10,少数种类可达100以上。15种硬骨鱼类的性比为1.3：1,性腺成熟度雄性Ⅲ期占37.4%,Ⅳ期占16.6%；雌鱼Ⅱ期占35.9%,Ⅲ期占28.4%,Ⅳ期占21.4%,Ⅴ期占11.4%,Ⅵ期占2.9%。推测这些种类中有少数种类如黄斑胡椒鲷、长吻裸颊鲷等的产卵期在春季,另外一些种类如胡椒鲷在春末夏初,其它多数种类则在夏季或秋季繁殖。这些种类的个体绝对繁殖力在30～450万粒,相对繁殖力80～850粒/g。鮨科种类繁殖力相对较低,笛鲷科种类较强。(4)测量了13种硬骨鱼类和2种软骨鱼类的年龄,其范围在2～12龄(没有测得1龄鱼),各个种类的优势年龄组均在3龄以上,表明在南海珊瑚礁水域的鱼类存在着较高年龄的群体。拟合了长度—重量关系,绝大多数种类的幂指数b值介于2.5～3.5,说明它们是匀速生长鱼类或接近匀速生长的鱼类。拟合了15种鱼的生长方程,绘制了它们的重量及其生长速度和加速度曲线。它们的绝对生长率基本表现为随着年龄的增长呈现先增加后减少的趋势,而相对生长率和瞬时生长率随着年龄的增长均呈下降趋势。(5)根据“年龄与生长”的分析结果,利用Beverton-Holt模型对13种硬骨鱼类进行种群动态评估。依据B-H模型单位补充量渔获量曲线,并结合鱼体生长规律、个体性成熟及资源利用等情况提出了它们的开捕年龄tc和开捕长度Lc,分别为黄斑胡椒鲷3.5 yr、428 mm,胡椒鲷3.0 yr、319 mm,长吻裸颊鲷4.8 yr、513 mm,红裸颊鲷2.4 yr、188 mm,杂色遗颊鲷2.1 yr、329 mm,黄鳍棘鲷3.2 yr、387 mm,白斑笛鲷3.0 yr、384 mm,星点笛鲷2.6y r、315 mm,紫红笛鲷2.2 yr、366 mm,红叉尾鲷1.9 yr、384 mm,日本紫鱼2.3 yr、224 mm,丝鳍紫鱼3.5 yr、355 mm,红钻鱼3.5 yr、433 mm。更多还原

【Abstract】 Coral reef is marine ecosystem with high productivity. Dongsha, Xisha, Zhongsha and Nansha Islands in South China Sea (hereinafter referred to as’SCS’) are typical coral reef ecosystem, which belong to one of ten global coral reef reserves partitioned in 2002. SCS’s reef-fishery is a unique fishery type among Four Seas—Bohai Sea, Yellow Sea, East China Sea and South China Sea, and it has its own special position and plays an important role both in marine fishery and maintenance of state sea right and benefit.There are few study on coral reef fishery resources in Dongsha, Xisha, Zhongsha and Nansha Islands because on-site survey is subject to many constraints such as remote distance, bad sea condition, special fishing method, given fishing season, as well as complicated geopolitics with neighbouring countries. Based systematic collection and document of historical data from different surveys of coral reef fishery resources in SCS, the study analyses large-scale distribution pattern of species diversity of fish in coral reef waters of the sea, addresses ecological distribution and catch distribution of some typical associated-reef fishes, in addition, it also examines reproduction, age and growth of some main commercial species and evaluates their population dynamics. And on the basis, the paper calculated optimum catchable size taking advantage of Y/R iso-catch curve of Beverton-Holt model and combining fish biological characteristics, which provide scientific references for development and sustainable utilization of associated-reef fish resources in SCS.(1) The analysis on large scale distribution pattern shows that there are 514 species recorded in Dongsha Islands,620 species in Xisha and Zhongsha Islands, and 548 species in Nansha Islands respectively. However, the number is lower than the expected one, also less than number of other reef waters where there are similar hatibats with SCS. Taxonomic diversity index of fish species was calculated. Average taxonomic distinctness index△+ in Dongsha, Xisha & Zhongsha and Nansha Islands is 55.1,60.2,56.6, respectively; and correspondingly, variation in taxonomic distinctness index∧+ is 121,164,150 in the three islands, respectively. All△+ values in three islands are less than that of the Northern Continental Shelf Waters of South China, but, on the contrary, all∧+ values are more than the Northern Continental Shelf Waters.(2) Considering comprehensively weight and individual composition proportion, catch rate in all survey sites, and index of relative importance (IRI) given by Pinkas, the paper introduces 10 species of Chondrichthyes—Carcharhinus limbatus, Hexanchus nakamurai, Sphyrna lewini, Triaenodon obesus, Hexanchus griseus, Isurus oxyrinchus, Squalus megalops, Carcharhinus longimanus, Galeocerdo cuvier and Taeniura meyeni, and 9 species of Osteichthyes—Plectorhinchus flavomaculatus, Plectorhinchus pictus, Lethrinus miniatus, Caranx stellatus, Ruvettus pretiosus, Caranx ignobilis, Etelis carbunculus, Pristipomoides filamentosus, Gymnosarda unicolor and Arothron stellatus, addressing their ecological distribution, and CPUE’s distribution in Xisha, Zhongsha and Nansha Islands waters.(3) Gonadal maturation data from 306 individuals of 21 species of Chondrichthyes and 1048 individuals of 93 species of Osteichthyes were examined. The result shows that the Chondrichthyes sex ratio is close to 1:1. The fact that stageⅡdominates in gonadal samples indicates reproduction time of most Chondrichthyes is not in the survey months, and that of a few species such as Carcharhinus limbatus and Centrophorus tessellates should be between May to July. According to available information and data collected in the survey, most of Chondrichthyes reproduce by means of ovoviviparity or zoogony with 1 to 10 embryos or even more than 100 ones, their pregnancy duration from 5 through 10 months or more time.The sex ratio of 15 species of Osteichthyes is 13:1. The statistics shows that stageⅢaccounting for 37.4%, stageⅣ16.6% for male, but to female, stageⅡamounting 35.9%, stageⅢ28.4%,Ⅳ21.4%,Ⅴ11.4%,Ⅵ2.9%, respectively. Some species such as Plectorhinchus flavomaculatus and Lethrinus miniatus reproduce in spring, another some like Plectorhinchus pictus in between late spring and early summer, and other most in summer or in autumn. Absolute fecundity of these species can reach at 300 to 4 500 thousand eggs, relative fecundity being 80 to 850 eggs per gram of body weight. Serranidae has lower fecundity, while Lutjanidae has higher reproductivty.(4) Age of 13 species of Osteichthyes and 2 species of Chondrichthyes were observed. Age distribution of the observed samples is 2 to 12 yr (with no 1 yr sample), and dominant age group of each species is more than 3 yr, which implies that there exist old populations in coral reef waters of SCS. According to fitting of Length-Weight relationship, B values of most of these species are between 2.5 to 3.5, indicating their growth is uniform or close to uniform. Growth equations of 15 species are fitted. The mapped growth speed (dL/dt and dW/dt) and accelerate speed (d2L/dt2 and d2 W/dt2) curves indicates that their absolute growth rates increase first and then decrease with age, but, on the contrary, relative growth rate and instantaneous growth rate decrease constantly at all times.(5) According research findings from "Age and Growth", population dynamics for 13 species of Osteichthyes are evaluated taking advantage of Beverton-Holt model. Catchable age tc and length Lc is calculated by Y/R iso-catch curve of B-H model and combining growth, gonadal development and maturation, and utilization of resources. The result shows that tc and Lc for Plectorhinchus flavomaculatus is 3.5 yr and 428 mm; Plectorhinchus pictus 3.0 yr and 319 mm, Lethrinus miniatus 4.8 yr and 513 mm, Lethrinus rubrioperculatus 2.4 yr and 188 mm, Lethrinella variegates 2.1 yr and 329 mm, Acanthopagrus latus 3.2 yr and 387 mm, Lutjanus bohar 3.0 yr and 384 mm, Lutjanus stellatus 2.6yr and 315 mm, Lutjanus argentimaculatus 2.2 yr and 366 mm, Aphareus rutilans 1.9 yr and 384 mm, Pristipomoides auricilla 2.3 yr and 224 mm, Pristipomoides filamentosus 3.5 yr and 355 mm, and Etelis carbunculus 3.5 yr and 433 mm.更多还原